Abstract: An airborne device for surveillance of an enclosed area, comprising a platform having illuminating imaging devices, and an attached lighter than air balloon. A vertically aligned rotor provides additional lift, a rotor directed along the length of the platform provides forward and backward motion, and additional rotors aligned sideways steer and rotate the device. The rotors are driven by electric motors powered by an on-board battery. A vertically directed distance sensor measures and controls the hovering distance of the device from the roof. A reel of optical fiber is installed at the rear end of the platform, and the optical fiber unwinds from the reel and deploys behind the device as it moves forward. This optical fiber carries image data back to a monitor. The length of fiber deployed, combined with directional and accelerometer readings can be used to determine the absolute position of the device.

Abstract: A method and system for optical communication between a transmitter and receiver, using a video camera to image the location of the remote transmitter. The comparatively slow frame rate of conventional detector arrays, which would limit communication rate, is overcome by reading only pixels in a region of interest around the transmission source image, and these pixels can then be read out and the communication information on them retrieved, at a frame rate much faster than that of the conventional full frame read-out. Custom wiring of the array can be used to enable implementation of this increased frame rate. Other methods of increasing communication speed using a video camera array detector include spreading the optical signal spatially along a row of pixels, and reading those pixels simultaneously in one frame, or wavelength multiplexing the optical information, and dispersing the different wavelengths onto successive pixels of the array.

Abstract: A system for the surveillance of terrain and the detection of intrusions over a plane extending into that terrain. A curtain array of light beams is projected along the plane and reflections from the terrain are detected by a sensor array essentially spatially coincident with the array of light sources. The times of flight of the beams are determined, and these characterize the form of the terrain being surveilled. The initial background reflection pattern is acquired and stored by the system. A sudden change in this detected background pattern can be defined as arising from an unexpected reflection, indicative of an intrusion. Signal processing systems are described utilizing modulated laser beams and detection at a frequency at least twice that of the modulation, such that reflected signals arising from the ON and the OFF periods of the laser modulation can be subtracted to eliminate the background signals.

Abstract: A system for making distance measurements of remote points using a phenomenon related to the time of flight of an illuminating beam. A modulated beam of light is directed at the target area. The modulated beam has temporally varying information impressed upon it, such that the time of flight of the beam to the target and back can be related to the temporal signature of the received beam. An acousto-optic modulator is used to perform frequency conversion of the modulated light reflected from points in the field, before that light impinges on the pixels of a detector array. The AO modulation frequency is close to the illuminating light modulation frequency, so that the converted mixed frequency falls within the limited parallel reading rate range of the detector array, and contains the temporal signature information of the modulated light received from the target within signals of manageable frequencies.

Abstract: An aerial platform comprising a kite providing a level of directional stability when elevated by the wind, and an inflated balloon attached above the kite with a cord. The payload is attached to the kite. The physical separation of the balloon from the kite isolates the payload from shocks generated by the balloon. Additional isolation is provided by use of an elastic attachment cord. Electric power is supplied to the aerial platform by means of an optical fiber receiving optical power from a ground-based source, and conversion of the optical power to electrical power on board the platform. In order to provide a strong tether line, the optical fiber is plaited with a jacket braided from high tensile strength fibers. An aerial laser transmitter is described using a ground based laser source transmitting laser power through an optical fiber to an aerial platform for transmission from the platform.

Abstract: A system for detecting intrusion across a surface, comprising a plurality of light sources projecting an array of illuminating beams along different optical paths in the surface and a detector array system directed such that it detects along a plurality of fields of view in the surface, illumination reflected from the illuminating beams. A signal processing system detects changes along the array of fields of view, in the reflected illumination level detected by the detector system. An increase greater than a predefined level in the reflected illumination level from any field of view provides an indication of an intrusion across the surveilled surface along that field of view, at the crossing point of the direction of that field of view with the optical path whose illuminating beam generated the increase in reflected illumination from that field of view.